[postgis-users] A table of DE-9IE patterns and types of topological relations

Jim Klassen klassen.js at gmail.com
Mon Apr 18 19:20:20 PDT 2022


It looks a lot better to me.

On 4/18/22 16:52, Martin Davis wrote:
> Is this any better?
>
> https://postgis.net/docs/manual-dev/using_postgis_query.html#DE-9IM
>
> On Mon, Apr 18, 2022 at 2:31 PM Jim Klassen <klassen.js at gmail.com> wrote:
>
>     As an aside, I am noticing these graphics probably aren't very accessible to people with vision impairments. There is a lack of meaningful alt-text, a general fuzziness/soft edges, and use of several colors of similar lightness.  In particular, the red is hard to separate out in grayscale and the red is the part that is most important as it is describing the part of the image that applies to that grid cell.
>
>     I'm not sure if it will come through on the list, but I've converted the 3x3 grid image from [1] to grayscale below as an example.  I know I'd have a very hard time picking out which section was what if I didn't already know the answer ahead of time.
>
>
>
>     [1] https://postgis.net/workshops/postgis-intro/_images/de9im3.jpg
>
>     On 4/15/22 15:08, Shaozhong SHI wrote:
>>     This is very interesting.
>>
>>     However, this needs to be further detailed with a table to explain a variety of cases and uses.
>>
>>     Regards,
>>
>>     David
>>
>>     On Fri, 15 Apr 2022 at 02:48, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
>>
>>         https://postgis.net/workshops/postgis-intro/de9im.html
>>
>>         > On Apr 14, 2022, at 4:35 PM, Shaozhong SHI <shishaozhong at gmail.com> wrote:
>>         >
>>         > The use of ST_Relate appears very attractive. However, there appears not yet a table detailing DE_9IE patterns and types of topological relations.
>>         >
>>         > There also appears that not much literature on the use of it for data quality assurance or things like deriving quality data from raw data.
>>         >
>>         > Can anyone enlighten me?
>>         >
>>         > Regards,
>>         >
>>         > David
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